InSight, NASA’s next Mars explorer, has arrived at Vandenberg Air Force Base in California – a big step forward in the countdown to T-zero on May 5, 2018. The spacecraft is called InSight – short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport – and it’s being tested, fueled and encapsulated for launch aboard the powerful United Launch Alliance Atlas V rocket. The upcoming liftoff will mark the first time an interplanetary mission has launched from the West Coast.